Pressing processes of this type are used, for example, in the pressing of pipe ends or shaft connections. High pressure is required because the friction of a tight fit has to be overcome and in many cases additional material deformation must be effected. A typical example is the pressing in and pressing out of collet chucks or clamping sleeves in corresponding tool holders or collet chuck holders for machine tools.
For certain embodiments of tool receptacles, in particular those having little or no conicity of collet chuck and receptacle cone, as are preferred for machines with very high speeds, the collet chucks or clamping sleeves with the inserted tool shaft cannot readily be inserted into the receptacle of the collet chuck holder and fixed with a clamping nut or, conversely, removed again after loosening of the clamping nut but must be pressed in and also pressed out again with high pressure. There are various solutions for this pressing in and pressing out but they are associated with disadvantages.
A pressing device which performs these tasks is described in Swiss Patent No. 896/06. To avoid requiring a complete pressing device for each different tool size, the tool receptacles are designed as changeable inserts which can be inserted into a corresponding recess in a housing. These inserts consist of lower and upper fixed plates and press plates displaceable in between by rams. The fixed plates and the displaceable press plates have engaging edges for placing on corresponding grooves or flanges on the parts to be pressed.
A disadvantage of this arrangement is that the inserts with the rams are relatively complicated to produce and therefore expensive.